Exhaust constituent sensors have been used for many years in vehicles to sense the presence of constituents in exhaust gasses (e.g., oxygen, hydrocarbons, nitrous oxides) and to sense, for example, when an exhaust gas content switches from rich to lean or lean to rich. Because exhaust constituent sensors are mounted to components of the vehicle exhaust flow system, the sensors must be durable and the sensors must be able to operate in a high temperature environment without being damaged by exposure to such high temperatures. The exhaust constituent sensors are typically installed in an exhaust pipe which is part of the vehicle's exhaust flow system and more specifically, the exhaust constituent responsive end of the sensor is disposed within an opening in the exhaust pipe so that exhaust gasses flow into the sensor and the level of the exhaust constituent to be sensed is communicated to a control system of the vehicle.
Due to the ramping up of emissions regulations related to off road recreational vehicles there has been an increase in applications of exhaust constituent sensors, particularly oxygen sensors, to these types of vehicles. Although all-terrain vehicles (ATVs) and multi-utility vehicles (MUVs) use engines very similar in type and layout to motorcycle engines, where the application of emissions equipment is well established, the exhaust systems used for such off road recreational vehicles differs in that the exhaust system is typically enclosed inside the body work of the vehicle. Furthermore, the body work is often plastic and requires special attention to dissipation of the heat generated by the exhaust system. Not only does the body work need protection from the heat generated by the exhaust system, the layout of the body work can also retain heat inside the body work thereby causing an increase in component temperatures. The exhaust constituent sensor is one of the components that need special care to prevent it from over heating. By way of example, a probe end of an oxygen sensor is subjected to the exhaust gas stream, and the heat from the exhaust gas is transferred by conduction along a body of the oxygen sensor. At the other end of the oxygen sensor are wires insulated with a plastic coating which can be adversely affected by the high temperatures generated by the exhaust system.